Campbell Scientific Sentek TriSCAN® Manual v 1.2a - Manual (Page 8)

TriSCAN Manual Version 1.2a
Copyright © 1991 – 2004 Sentek Pty Ltd All rights reserved Page 1
Introduction
TriSCAN: Sentek’s Fertilizer/Salinity and Soil Water Monitoring
System
Monitoring, understanding and managing irrigated water and nutrients, so that they stay within the active
crop’s root zone, is one of the key challenges in modern agriculture. This is necessary in order to develop
long term, environmentally sustainable irrigation and land management practices.
Today electronic sensor technology can be used in conjunction with analytical software to visualize and
prevent leakage of water and nutrients from production systems into water tables and waterways through
precision irrigation management.
Sentek Pty Ltd has developed a near continuous in-field fertilizer/salinity and soil moisture monitoring
system called TriSCAN in order to help irrigators and land managers to efficiently utilize precious water
resources and fertilizer. Implementation of this technology can lead to management of fertilizer, salinity and
water movement to the benefit of the environment. It also has the potential to contribute to substantial
savings in water, fertilizer and power (pumping costs) while at the same time increasing crop yields, quality
and farm profits. Sustainable and profitable agriculture is the goal.
The TriSCAN sensor monitors soil water content and soil salinity on a near continuous basis. Sensors are
placed at multiple depths on probes within the soil profile. Probes are connected to a data logger, where the
data is recorded. Graphed data of soil water content and salinity of each depth level can be viewed
simultaneously.
This manual describes the operation and use of the TriSCAN multi-sensor, profile probe and its data output,
in the context of fertilizer, salinity and irrigation management. It introduces important definitions and terms,
explains the problem and touches on the national and global impacts of salinity. It also stresses the
importance of understanding the link between fertilizer management and salinity. TriSCAN features and
applications are described, along with an explanation on how the sensor works. Known sensor specifications
are provided.
The manual also covers principles of site selection, and details the process of configuring the probe for
connection to a range of different logging systems. Data from these systems can be imported into Sentek’s
customised irrigation and salinity management software, IrriMAX
®
6 for graphical display.
A further section of the manual covers how to benchmark the TriSCAN salinity measurement units
(Volumetric Ion Content, VIC), against the Systéme Internationale (SI) unit for electrical conductivity
(deciSiemens per metre, dSm
-1
).
The manual closes with a collection of useful appendices and references.
The manual should be used in conjunction with the SDI-12 and RS485 Modbus technical manuals, which
provide information on the interfaces, power consumption and wiring diagrams.
Important Definitions and Terms
The term salinity in this manual refers to the total dissolved concentration of major inorganic solutes or ions
(principally Na
+
, Ca
2+
, Mg
2+
, K
+
, NH
4
+
NO
3
-
, HCO
3
-
, CO
3
=
-, SO
4
=
and Cl
-
) in aqueous samples. As applied to
soils, it refers to the soluble plus readily dissolvable salts in the soil, or in an aqueous extract of a soil
sample.
Ions can be classified in terms of the nature of their charge:
Anion - a single atom or molecule with a net negative charge.
Cation - a single atom or molecule with a net positive charge.